Main chain structural similarity for tetragonal thermolysin cooled with different methods in the presence of 50% xylose. The plots show distributions of the differences (Delta) in distances from the center of mass (CM) for every Cα in the pair of structures (Frauenfelder et al., 1987). The LT versus RT distributions show an average positive value since the LT structures have smaller distances due to thermal contraction. The distributions versus RT are similar for plunge and gas stream cooling. The distribution for the LT plunge versus LT gas stream conformations is about 3–4× narrower than the LT versus RT distributions. Considered together these results suggest that the two cooling methods have very similar impacts on the main chain conformation of the protein. The RT structure was PDB entry 5un3 (Juers et al., 2018), for which X-ray data were collected on a crystal soaked in 50% xylose. The LT structures used in the plots are reported here and differ in cell volume by 0.1%. Using the previously reported gas stream cooled structure for 50% xylose (PDB entry 5uua; Juers et al., 2018), which differs in cell volume from the two LT structures reported here by 0.1–0.2%, gives similar results.